Self-adhesive laminate and method of making it

ABSTRACT

A decorative laminate includes a laminate substrate coated with an adhesive layer. The adhesive layer is a layer of a physically setting, solvent-free adhesive material including an acrylic polymer. The adhesive layer is self-adhesive at room temperature. The adhesive-coated laminate substrate has a peeling-off force of at least 0.2 N/mm 2 , after application on a carrier. A method for the production of the adhesive-coated laminate substrate, its use as a coating material, and a composite of the adhesive-coated laminate substrate and a carrier material are also provided.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/272,991, filed on 14 Nov. 2005, which in turn claims priority under35 U.S.C. §119(e) to U.S. Provisional Patent Application 60/652,257,filed on 11 Feb. 2005, and which also claims priority under 35 U.S.C.§120 as a continuation of International Patent ApplicationPCT/EP2004/009001, filed 12 Aug. 2004. International PatentPCT/EP2004/009001 in turn claims priority based on German Application DE2003 103 7531, filed 14 Aug. 2003. The disclosures of these relatedpatent applications are hereby incorporated by reference herein in theirentirety and made a part hereof, including but not limited to thoseportions that specifically appear hereinafter.

FIELD OF THE INVENTION

This invention relates to a decorative laminate substrate that is coatedwith a self-adhesive layer of an adhesive material including an acrylicpolymer. Furthermore, the invention concerns a method for the productionof such a laminate.

BACKGROUND OF THE INVENTION

Laminated sheets (otherwise referred to as “laminate substrates”) aregenerally used for decorative purposes in many areas of daily life. Theyare used, for example, in interior construction for the covering orlining of windows, stairs, and floors, and in the coating of furniture,both in the private as well as in the commercial sectors.

Laminated sheets often are made of cellulose sheets impregnated withcurable synthetic resins and pressed with heat under high pressure. Oneor more sheets on one or two sheet sides exhibit decorative colors ordecorations. Such laminated sheets (known as high pressure laminates orHPL) are sold, for example, by Resopal GmbH (a Wilsonart Internationalcompany), under the tradename RESOPAL®.

The application of the laminated sheets on a carrier substrate such aschipboard, fireboard, or plywood used for wall, floor or ceilingfinishes or other objects, can be done with an aqueous adhesive.Depending on the type of the adhesive, various conditions must beprecisely maintained, so as to obtain a coating of good quality andstability. According to known application methods, the laminated sheetsand the carrier are typically joined together after the application ofthe adhesive, immediately or after a short waiting time. The joiningtogether is done according to the previous methods under a pressingpressure of 2 to 5 bar and at a temperature of up to 120° C.

Furthermore, the adhesive application is typically uniformly distributedover the laminated sheet and/or carrier surface, so as to avoid warpphenomena. This is particularly true for water-containing adhesivesystems, in which the application quantity is to be kept as low aspossible.

With a nonuniform adhesive application and an inexact maintenance of thepressing pressure, pressing temperature, and/or pressing time,unsatisfactory results can be obtained during the cementing. Thus, forexample, excessively high temperatures can lead to warping and materialdamage. Low temperatures or pressures often result, on the other hand,in an insufficient adhesion. Depending on the adhesive system, thepressing pressure and the pressing temperature typically must bemaintained between a few minutes and up to several hours. If necessary,one must wait overnight to obtain a final curing.

Working with solvent-containing contact adhesives generally requiresadherence to work protection and accident prevention regulations.Furthermore, the use of solvent-containing adhesives is generallyclassified as problematic from a health and environmental policyviewpoint. The use of dispersion adhesives on a water basis, such ascasein glue, frequently leads to the partial swelling of the carriersurface, which is frequently the case, for example, when usingparticleboard as the carrier material. As a result, a slightlycorrugated or nonuniformly plane surface is obtained. Furthermore, thedrying of water- or solvent-containing adhesives may require severalhours.

Reaction adhesive, such as epoxide, polyesters, or polyurethaneadhesives, are also of concern with respect to health and require aprecise knowledge and maintenance of the processing conditions.

The previous adhesives and adhesive methods typically require a highequipment outlay, such as, for example, for the use of uniform and highpressing pressures and for the maintenance of the temperature. Dependingon the adhesive, the curing, e.g., until a sufficient adhesive isattained, can require several hours.

The circumstances mentioned above often make the use and the successfulprocessing of laminated sheets relatively difficult, particularly forthe private sector or in the craftsman's sector. There is a need for animproved, efficient, safe, and less expensive decorative laminate panel.

SUMMARY OF THE INVENTION

A general object of this invention is to provide an improvedadhesive-coated laminate substrate, particularly for use as a decorativeor protective laminate covering for a material, such as wood, metal ormineral boards.

A more specific objective of this invention is to overcome one or moreof the problems described above. In addition to the needs of thecommercial sector, the needs of the private user with regard to a simpleprocessing or application are considered and met.

Another object of this invention is to provide a decorativeadhesive-coated laminate substrate, which adheres rapidly and firmly ona carrier substrate surface, without having to accept the long waitingtimes.

The rapid and firm adhesion of the laminate on the carrier can beachieved without the use and precise maintenance of high pressures orhigh temperatures during the application.

Another object of this invention is simplifying or eliminating thehandling and application of the adhesive on the carrier. In particular,the difficulty of obtaining a uniform application of the adhesive on thecarrier is avoided by instead uniformly applying the adhesive to thelaminate substrate.

Furthermore, it is an object of this invention to provide a decorativelaminate substrate that can be cemented without the use of water orsolvents, and is as unobjectionable as possible from a health viewpointand with regard to safety aspects.

Finally, it is an object of this invention to provide a decorativelaminate substrate, which, after application on a carrier, provides auniform planar surface.

The general object of the invention can be attained, at least in part,through an improved decorative laminate substrate coated with anadhesive layer. The adhesive layer may include a layer of a physicallysetting, solvent-free adhesive material including an acrylic polymer.The adhesive layer is self-adhesive at room temperature.

The invention further comprehends a laminate including a laminatesubstrate, a non-pressure sensitive adhesive layer applied to thelaminate substrate, and a self-adhesive layer applied to thenon-pressure sensitive adhesive layer. The non-pressure sensitiveadhesive layer serves as a barrier layer (e.g. “primer”) to preventpenetration of the self-adhesive layer into the laminate substrate, andto provide the laminate substrate with a primed surface. Theself-adhesive layer includes a layer of a physically setting,solvent-free adhesive material comprising an acrylic polymer. Theself-adhesive layer is self-adhesive at room temperature, meaning itdoes not require heat for activation, and may be manually activated uponcontact with a carrier with or without pressure, or with light manualpressure.

The present invention also includes a method for the production of thelaminate of this invention.

Furthermore, a composite material of a carrier and the adhesive-coatedlaminate substrate and the use of the adhesive-coated laminate substratefor the coating of carriers are provided.

A decorative laminate with an adhesive layer is made available, which ischaracterized in that the adhesive layer is a layer of a physicallysetting, solvent-free adhesive, which is self-adhesive at roomtemperature, wherein the laminated sheet has a peeling-off force of atleast 0.2 N/mm² after the application on a carrier at room temperature.It is possible, in a manner which was not readily predictable, to makeavailable a laminate, which quickly and firmly adheres on a carrier,without having to accept long waiting times.

Furthermore, the following advantages are attained by this invention.The application of the adhesive-coated laminate substrate on the carriercan be done without the use of high pressures and increasedtemperatures. A simple short pressing pressure, for example, manually,on the adhesive-coated laminate substrate is generally sufficient forimmediate adhesion to the carrier. In addition, the adhesive-coatedlaminate substrate adheres stably on a carrier. Thus, one obtains, forexample, a very high peeling-off force of the adhesive-coated laminatesubstrate from the carrier. Furthermore, a high peel resistance and ahigh static shearing strength are attained. Also with a temperature loadof the composite of the adhesive-coated laminate substrate and carrierover a longer time, the adhesion remains stable and no peeling of thedecorative adhesive-coated laminate substrate from the carrier appears.The adhesion characteristics, such as the peeling force, the shearingstrength, and the peel resistance also are essentially retained with atemperature load. The previously mentioned characteristics are alreadyattained with a small application quantity or layer thickness of theadhesive so that it can be used in a manner which saves material.Another advantage is to be found in that the adhesive application neednot be undertaken by the end user himself. The reverse of the laminatesubstrate is already provided with the adhesive and can be immediatelyprocessed—that is, be applied on the carrier, without processingconditions of the adhesive, a uniform application, etc., having to beobserved. The laminate substrate already provided with adhesive, inaccordance with the invention, can be stored over a relatively longtime. It is not necessary to apply the laminate substrate to the carrierimmediately after application of the adhesive, as is typically the casewith previous adhesive systems. The adhesive-coated laminate substrateof this invention provides a particularly uniform and planar surfaceafter application on a carrier. In addition, the use of solvents anddispersants during the cementing of the plate, in accordance with theinvention, can be dispensed with, which is particularly advantageouswith regard to environmental and health aspects. Finally, the adhesiveused, in accordance with the invention, contains only not very volatileplasticizers with a relatively low evaporation.

The previously mentioned advantages provide a relatively simple and easyto install adhesive-coated laminate substrate for the private user andthe craftsman without mechanical equipment. The processing can beundertaken directly on site, without machines or special apparatuseshaving to be used for the processing. By the simple and rapidpossibility of the application, the adhesive-coated laminate substratein accordance with the invention is suitable, in particular, also, forthe home user, to upgrade and cover furniture, door surfaces, walls,etc.

Other objects and advantages will be apparent to those skilled in theart from the following detailed description taken in conjunction withthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a process for preparing anadhesive-coated laminate substrate of the invention.

FIG. 2 schematically illustrates an alternative process for preparing anadhesive-coated substrate laminate of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a decorative laminate substrate having aself-adhesive layer applied, either directly or indirectly, to one sideof the laminate substrate. In one embodiment of this invention, theself-adhesive layer, at room temperature, includes a physically applied,solvent-free adhesive material including an acrylic polymer. Theadhesive-coated laminate substrate of this invention provides improvedbond strength or adhesion, temperature and humidity resistance, andadequate shear or creep resistance when bonded to a carrier. Theadhesive-coated laminate substrate is relatively easily applied by theend user, as compared to typical known adhesive systems.

In accordance with the invention, “laminate substrate” includesmaterials such as, for example, glass fiber fabrics, paper, wood,textiles, plastic films, paper base laminates, laminated fabrics,laminated wood, which are produced by a buildup (the so-calledlaminating) of paper or fabric strips or glass fiber mats, soaked orcoated with synthetic resins, such as epoxy, melamine resins,thermoplastics, phenoplastics, urea-formaldehyde resins, and by usingpressure and heat. They are designated, in the state of the art, as“laminates” also, and are used in diverse embodiments, such as plates,round rods, tubes, long and construction molded articles, for manydifferent uses, such as printed circuits, for aircraft, motor vehicle,boat construction, weather-resistant covers, sports gear (for example,skiers) and decorative purposes.

In one embodiment of this invention, the use of a high-pressure laminate(“HPL”) as the laminate substrate has proved to be very particularlyadvantageous. The HPLs have layers of fibrous strips, preferably, paper,impregnated with curable resins, and optionally, one or more decorativelayers, wherein the decorative layers are provided with decorativecolors and/or patterns and preferably, are impregnated with resins on amelamine basis. The strips are bonded together under heat and highpressure of about 5 mPa or greater. In accordance with the invention, acontinuously produced laminate (CPL) can also be used as the laminatesubstrate.

As will be appreciated by one skilled in the art following the teachingsherein provided, various and alternative types, shapes, configurationsof laminate substrates are available for use in the laminate of thisinvention. Such alternatives and details regarding the above materialscan be found, for example, in the current technical literature, forexample, “Ullmann's Encyclopedia of Industrial Chemistry,” 4th Edition,Vol. 15, p. 326, and the norms DIN EN 438, Part 1 to Part 6, ISO 4586-1and ISO 4586-2, each herein incorporated by reference in its entirety.

In one embodiment of this invention, the laminate substrate is adecorative high-pressure laminate preferably produced by a method inwhich fibrous strips are impregnated with at least a curable resin andthen are pressed by the simultaneous use of heat, advantageously at atemperature in the range of about 120° C. to about 150° C., and at apressure of at least 7 mPa, so that the resins initially flow andsubsequently harden. A homogeneously closed material with an increaseddensity, advantageously about 1.35 g/cm³, and the desired surfacecharacteristics is desirably obtained. Within the scope of this method,discontinuous multi-stage presses are used.

In another embodiment of this invention, a laminate substrate in whichthe fibrous strips are impregnated with heat-curable resins and then arecontinuously pressed on double-band presses at a high temperature,preferably, in the range of about 140 to about 200° C., has provedparticularly advantageous. Such a method is particularly useful inproducing continuously produced laminates (CPLs).

In another embodiment of this invention, a plastic laminate, inparticular, polyester laminates made of paper strips, which areimpregnated with at least one polyester resin, is used as a laminatesubstrate. One or both laminate sides thereby advantageously have adecorative paper, impregnated with polyester resin. The production ofthese polyester laminates advantageously takes place continuously.

The thickness of the laminate substrate of this invention can beselected freely, in principle, according to the field of application; itis generally in the range of 0.2 mm to 20 mm or 0.3 to 15 mm. Moredesirably, the thickness can also be in the range of 0.5 mm to 3.0 mm orin the range of 0.6 to 2.5 mm. In one embodiment, the thickness 0.6 to1.6 mm is particularly desirable and 0.6 to 1.2 mm is even moredesirable.

In one particularly preferred embodiment of this invention, a physicallysetting, solvent-free adhesive material is used to form a self-adhesivelayer on at least one side of the laminate substrate. As used herein,“solvent-free” refers to an applied adhesive layer that contains nowater and no organic liquids, which act as solvents or dispersants. Inone embodiment, the self-adhesive layer is formed at least in part of anadhesive material including an acrylic polymer or copolymer.

In one particularly preferred embodiment of this invention, the adhesiveincludes a terpolymer of vinyl acetate-ethylene and acrylic. An exampleof such a terpolymer is available from Air Products and Chemicals, Inc.,Allentown, Pa., and sold under the tradename FLEXBOND 153. OtherFLEXBOND adhesives, such as, for example, FLEXBOND AF75 and FLEXBONDEAF60 are useful in forming laminates of this invention.

In one embodiment of this invention, the self-adhesive layer includes atleast one elastomer, at least one not very volatile plasticizer, and atleast one hydrocarbon resin. Additional component(s) of the adhesivelayer can be a elastomeric components selected from the natural rubbers,polyisobutylene rubber, ethylene-propylene rubber (EPR),styrene-butadiene rubber, ethylene-propylene-diene-terpolymer rubber(EPDM), butyl rubber, ethylene-vinyl acetate copolymer,ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylatecopolymer, ethylene-(meth)acrylic acid-(methy)acrylate terpolymer, andacrylate rubbers. The elastomer can also be a block copolymer asdescribed below. The elastomeric component(s) can be combined with theacrylic polymer, i.e. a polymer which includes an acrylic and/oracrylate group, e.g. the vinyl acetate-ethylene-acrylic terpolymerdescribed above. Other elastomers may be combined with the acrylicpolymer.

In one preferred embodiment of this invention, an additional elastomeris a high molecular weight polyisobutylene rubber with a number-averagemolecular weight of about 300,000-3,500,000 g/mol, desirably about400,000-1,500,000 g/mol, and more desirably about 800,000 g/mol(according to GPC). The polyisobutylene rubber can be copolymerized withone or more comonomers, which are selected from styrene,ring-substituted styrenes, divinylbenzene, isoprene, indene,1,3-butadiene, cyclopentadiene. The fraction of isobutene in thepolyisobutylene rubber is desirably about 90%.

In one embodiment of this invention, the total weight fraction of theelastomer is about 10 to about 70 wt %, relative to the dry weight ofthe adhesive, and preferably about 30 to about 60 wt %. Of this amount,the acrylic polymer (e.g. the vinyl acetate-ethylene-acrylic terpolymer)should constitute at least about 10% by weight of the adhesivecomposition, and may constitute up to about 70% by weight depending onwhether or not other elastomers are also present. The balance of theadhesive composition includes about 15-40% by weight of the plasticizer,about 15-30% by weight of the hydrocarbon resin, and about 0.01-2% byweight antioxidant.

The plasticizer can be a low-molecular weight polyisobutylene with amolecular weight of about 800 to about 5000 g/mol. The weight fractionof the low-molecular weight polyisobutylene can be about 18 to about 25wt %, relative to the total weight of the adhesive.

In accordance with one embodiment of this invention, isobutylenepolymers which can be used in the adhesive can be obtained from BayerAG, under the tradenames BAYER BUTYL (a copolymer of isobutylene andisoprene) and POLYSAR BUTYL XL (a copolymer of isobutylene, isoprene,and divinylbenzene).

In accordance with one embodiment of this invention, block copolymerscan be used as the elastomer which have at least two end blocks of avinyl-aromatic monomer (block A) and at least one middle block (blockB), which contains either a conjugated diene or is formed from anethylene-butylene copolymer or an ethylene-propylene copolymer. Theconfiguration can be linear, grafted, or star-shaped, depending on themethod of production.

Typical block copolymers with the simplest conformation have thestructure polystyrene-polybutadiene-polystyrene (SBS) orpolystyrene-polyisoprene-polystyrene (SIS), orpolystyrene-polyethylene/polybutylene-polystyrene. A typical radial orstar polymer comprises one in which the B-block has three or fourbranches (radial) or more branches (star).

The end blocks A of the copolymer are formed from one or morevinyl-aromatic monomers, which are advantageously selected from styrene,ring-alkylated styrenes, such as alpha-methylstyrene and vinyltoluene,and polycyclic vinyl-aromatic compounds, such as vinylnaphthalene.Styrene and alpha-methylstyrene are preferred. Styrene is especiallypreferred. A block which is built as the end block A, can also bepresent, once or several times, in the middle of the polymer chain, inaddition to being at the ends.

If the middle block B of the block copolymer contains a conjugateddiene, it can be a homopolymer of a conjugated diene, a copolymer fromseveral conjugated dienes, or a copolymer from a conjugated diene and avinyl-aromatic compound, such as styrene or alpha-methylstyrene, as longas the conjugated diene predominates. The conjugated diene is preferablyselected from a compound with 4-8 carbon atoms, such as butadiene,isoprene, 2,3-dimethyl-1,3-butadiene and piperylene, wherein butadieneand isoprene are preferred.

If block B contains a conjugated diene, it can be partially orcompletely hydrogenated. In addition, the A-blocks can also be partiallyor completely hydrogenated.

The average molecular weight of an A-block is about 5000-125,000 g/mol,and preferably about 6000-60,000 g/mol (weight average according toGPC). The average molecular weight of a B-block is about 10,000-300,000g/mol and preferably about 30,000-150,000 g/mol (weight averageaccording to GPC). The total weight of the block copolymer is desirablyabout 25,000 to about 350,000 g/mol, more desirably about 35,000-300,000g/mol (weight average according to GPC). Advantageously, the fraction ofthe A-block is about 5-65 wt %, and more desirably about 35-50 wt %,relative to the block copolymer. Another advantageous range is about5-30 wt %.

Details of the production of the aforementioned block copolymer can befound, for example, in the documents EP 0 537 115 A1 and U.S. Pat. Nos.3,239,478; 3,427,269; 3,700,633; 3,753,936; and 3,932,327, thedisclosure of each being herein incorporated by reference in itsentirety.

The aforementioned polymers can be used individually or in combinationwith one another.

When used as an additional thermoplastic elastomer, the weight fractionof the block copolymer is desirably about 5-50 wt %, and more desirablyabout 10-40 wt %, relative to the total weight of the adhesive. A moredesirable range of the weight fraction of the block copolymer is about12-25 wt %, and more desirably about 15-20 wt %. Another advantageousrange for some applications is about 30-40 wt %.

Exemplary block copolymers which can be used within the scope of oneembodiment of this invention, without limitation, can be obtained, underthe tradenames KRATON G1650, G1651, G1652, G1657, G4309 (linearstyrene-ethylene/butylene-ethylene block copolymers of different blocklengths), KRATON RP-6906, KRATON DX1122, AND KRATON D1118X. Thesepolymers are available from Craton Polymers, LLC.

To build up the pronounced long-term tackiness, the adhesive, in oneadvantageous embodiment, contains synthetic plasticizers with a lowvolatility (evaporation loss or migration) at high temperatures (greaterthan about 120° C.).

The plasticizers contained in the adhesive are desirably syntheticplasticizers with a high boiling point and vapor pressure, which are notvery volatile and exhibit an only slight evaporation from the adhesive.

Plasticizers are advantageously selected from mineral oils, paraffinoils, olefin oligomers, and polymers with lower molecular weights. Asoligomers, one can use, for example, polypropylenes, polybutenes (e.g.the low molecular weight polyisobutylene described above), hydrogenatedpolyisoprenes, hydrogenated butadienes, etc., wherein the molecularweight is advantageously about 350 to about 10,000 g/mol.

The weight fraction of plasticizers is desirably about 0-40 wt %, andmore desirably about 15-40 wt %, or about 15-30 wt %, relative to thetotal weight of the adhesive.

Furthermore, hydrocarbon resins can optionally be added to the adhesive,in order to attain a pronounced surface tackiness. The surface tackiness(tack) makes possible a pronounced tackiness in connection with lowpressing forces during the assembly.

A group of the hydrocarbon resins (tackifiers), contained in theadhesive, desirably include natural and modified resins, such as, forexample, gum resin, wood resin, tallow oil resin, distillate resin, androsin, hydrogenated resin, dimerized resin, and polymerized resin.

Likewise, glycerol and pentaerythritol esters of natural and modifiedresins, such as the aforementioned, can be used.

Other resins which can be used in the adhesive as tackifiers arepolyterpene resins, hydrogenated polyterpene resins, copolymers andterpolymers of natural terpenes, such as styrene/terpene,alpha-methylstyrene/terpene, and vinyltoluene/terpene. Also usable arephenol-modified terpene resins, which can be obtained, for example, bythe condensation of a terpene and a phenol. Finally, aliphatic,cycloaliphatic, aromatic and aliphatic/aromatic resins based onpetroleum can also be used as the hydrocarbon resin. Other resins whichcan be used in accordance with the invention and are known to thespecialist are mentioned in the document EP 0 537 15 A1, the disclosureof which is herein incorporated by reference in its entirety.

The weight fraction of the hydrocarbon resin can be about 0-80 wt %,relative to the total weight of the adhesive, more desirably about 10-50wt %, and even more desirably about 15-30 wt %.

In one embodiment of this invention, the self-adhesive layer and/oradhesive material can, optionally, contain common stabilizers,antioxidants, and other auxiliaries, fillers, and/or additives, knownand available to those skilled in the art. Antioxidants canadvantageously be selected from the hindered phenols and multifunctionalphenols, such as sulfur- and phosphorous-containing phenols. An overviewof such stabilizers and additives is given in the documents U.S. Pat.No. 6,143,818, and EP 0 537 115 A1, the disclosures of which are eachincorporated by reference herein in their entirety. The weight fractionof stabilizers is desirably about 0.1-2 wt %, relative to the totalweight of the adhesive, and preferably about 0.1-1 wt %.

The self-adhesive laminate of this invention desirably has a hightackiness, a strong immediate adhesion (tack), and also a high cohesionand good shear or creep resistance. As a result of the lattercharacteristics, the applied adhesive layer or the applied laminate canbe loaded mechanically. Advantageously, in one embodiment of thisinvention, the applied adhesives are also resistant to water, weakacids, and alkalis. Using adhesive materials that are free of water orother solvents or dispersants means that with a carrier substrate havingan absorbing capacity, they do not produce any swelling of the materialdue to the liquid. In one embodiment of this invention, the adhesivesused are swell-free.

In one embodiment of this invention, those previously describedadhesives are used, which have a solids content of about 100%, a densityof about 1 g/cm³ (at 20° C.), a viscosity at 160° C. of about15,000-65,000 mPas, a processing temperature of 150-190° C., a softeningpoint of about 90-135° C. (DIN 52011), a static shearing resistance atroom temperature of about 5-15 kg (based on DIN EN 1943), a peeling-offresistance of about 35-65 N/25 mm (based on DIN EN 1939), and a shearingstrength loss temperature (measurement method, see examples below), ofabout 60° C. to about 105° C., and more desirably about 65° C. to about97° C.

In a particularly preferred embodiment of this invention, the adhesivelayer applied on the laminated sheet is covered, for protection, with arelease layer, which preferably is made, for example, of a siliconizedpaper or film. In this state, the sheet can be stored for a long time,desirably up to 12 months, without losing its adhesive characteristicsor undergoing some appreciable decline.

The application quantity, or add-on level, of the previously describedadhesive on the laminate substrate is generally about 80 to about 300g/m², desirably about 140 to about 240 g/m², and more desirably about150 to about 200 g/m². In one embodiment of the invention, the add-onlevel of the adhesive layer is from about 75 to about 150 g/m².

The layer thickness of the self-adhesive layer on the laminate substrateis generally about 0.05 to about 0.50 mm, or about 0.08 to about 0.30mm, more desirably about 0.14 to about 0.24 mm, and particularly about0.15 to about 0.20 mm. In one embodiment of the invention, theself-adhesive layer is about 0.175 mm thick. If both a self-adhesivelayer and a non-pressure sensitive adhesive layer are used, each layermay have a thickness of about 0.125 mm. The adhesive layers can beapplied using a roller coater or other suitable coating device. Eachadhesive layer is desirably applied to the release layer or laminatesubstrate as a water-based emulsion; however, the adhesive layer can beapplied using organic solvent-based emulsions or hot-melts. The adhesivelayer is desirably applied to the release paper first, and then dried,although the adhesive layer can also be applied to the laminatesubstrate first. Upon application of the adhesive emulsion, the adhesiveis dried, such as at 100° C. for 5 minutes, to form the appliedsolvent-free adhesive layer.

The pressing time upon application of the adhesive-coated laminatesubstrate is, in accordance with the invention, less than 5 seconds.Advantageously, a pressing time of 1 to 3 seconds is sufficient forbringing about an adhesion to the carrier with the mechanicalcharacteristics mentioned in the following.

The necessary pressing pressure in the application of theadhesive-coated laminate substrate on the carrier surface is, inaccordance with one embodiment of this invention, at most 2 bar.Desirably the needed pressing pressure is from about 0.2-1 bar and moredesirably about 0.3-0.6 bar. In general, a light pressure, manually, issufficient, in order to attain a complete adhesion. With largersurfaces, a uniform pressure using a roller is advantageous.

The application of the adhesive-coated laminate substrate of oneembodiment of this invention is preferably carried out in thetemperature range of about 5° C. to about 35° C. Advantageously, theadhesive-coated laminate substrate can be applied on a carrier at roomtemperature.

In one embodiment of this invention, the peeling-off force, which isneeded to peel off the adhesive-coated laminate substrate applied on acarrier from the carrier, is at least about 0.2 N/mm². Desirably thepeeling-off force is about 0.2 to about 2 N/mm³, and more desirablyabout 0.5 to about 1.5 N/mm², and even more desirably about 0.8 to about1.2 N/mm². These values of the peeling-off force are desirably attainedwhen the adhesive-coated laminate substrate is applied at roomtemperature with the aforementioned pressing pressures, or by means of alight pressure, manually or with a roller. The peeling-off force isdetermined according to the method described in the European norm EN311, herein incorporated by reference in its entirety.

Alternately, the peeling-off force can be increased in that the pressingpressure is increased above the aforementioned value ranges. This is,however, not necessary for the invention and can be optionally carriedout, if desired.

Likewise, the peeling-off force of the adhesive-coated laminatesubstrate from the carrier can be increased in that the laminatesubstrate and the adhesive layer are heated shortly before or during thecementing on the carrier. This measure is not necessary and merelyoptional. Furthermore, the peeling-off force can be affected if thesurface of the laminate substrate on which the adhesive is applied isroughened with the usual grinding agents before the application of theadhesive.

Finally, it can be advantageous but not necessary to pretreat thesurface of the laminated substrate on which the adhesive is applied withthe usual adhesion priming agents for adhesives, namelyadhesion-imparting, preliminary paints or primers. Common adhesionpriming agents include, for example, ethylene-acrylamide copolymers,polymeric isocyanates, and reactive silicon-organic compounds.

The adhesive-coated laminate substrate of one embodiment of thisinvention is characterized in that up to a temperature load of 80° C.over at least 2 hours, a peeling of the laminate substrate from acarrier material, in particular, from a particle board, does not appear.In particular, a peeling is not observed with a composite of thelaminate, in accordance with the invention, and a carrier after at leasta two-hour temperature load of about 50° C. to about 70° C. Theadhesive-coated laminate substrate has been tested by introducing asample laminate substrate applied on a carrier into a furnace at roomtemperature, which is filled with ambient air. This means that the airin the interior of the furnace has the same temperature and moisturecontent as the ambient air. Exemplary conditions are a temperature ofabout 20-23° C. and a relative humidity of 60-65% at the beginning ofthe test. Subsequently, the furnace is closed and heated to 80° C., andis maintained at this temperature for at least 2 hours.

The adhesive-coated laminate substrate of this invention can be appliedon different types of carriers, wherein the type of carrier is notparticularly limited. Preferred carrier materials are melamine-coatedparticle boards, carrier plates coated with laminate, chip board,medium-density fibrous plates, hard fibrous plates, plywood boards,veneer sheets, solid wood, honeycombs, foams, metal plates, sheet metal,mineral carriers, natural and synthetic rock, tiles, and gypsum plasterboard.

This invention further contemplates and includes a composite material,which comprises one of the previously mentioned carriers and anadhesive-coated laminate substrate which adheres to the carrier. Thelaminate substrate can advantageously be applied both onliquid-absorbing (absorbent) carriers, such as uncoated particle boardsand uncoated wood, as well as on non-liquid-absorbing (nonabsorbent)carriers, such as metals, ceramic, glass, coated woods, coated particleboards etc.

The composite of one embodiment of this invention is characterized by auniform and planar surface on the sides of the applied laminatesubstrate. Thus, the maximum height difference on the sides of thedecorative layer is about 0.05-0.5 mm, and more desirably about 0.05-0.2mm. The uniformity can easily be determined, in actual practice, byvisual inspection, such as by the undistorted reflection of a lightsource (for example, neon tube) on the surface of the laminate substrateapplied on the carrier.

The adhesive-coated laminate substrate applied, in accordance with oneembodiment of this invention, on a carrier generally has a more uniformand more planar surface, as compared to laminate substrates appliedusing conventional methods/adhesives on carriers.

Particularly advantageous, this characteristic manifests itself, if theadhesive-coated laminate substrate is applied on an absorbent orliquid-absorbing carrier. In this case, the laminate substrate forms amore uniform and more planar surface than a sheet that was applied witha solvent- or dispersant-containing adhesive.

In another aspect, the invention under consideration concerns the use ofthe previously described adhesive-coated laminate substrate for thecoating of a carrier material which is preferably selected from thepreviously mentioned carrier materials. The used carrier can be bothliquid-absorbing (absorbent) and also non-liquid-absorbing.

Likewise, the invention concerns the use of the composite of the carriermaterial and the adhesive-coated laminate substrate in interior andoutside construction, such as for the covering of walls, ceilings, anddoors, and for the production and covering of furniture and pieces offurniture.

Due to the previously described adhesion characteristics of theadhesive-coated laminate substrate on the carrier material, especiallyon particle boards, and the peeling-off resistance with a temperatureload, the composite is also suitable for the production of pieces offurniture which are temporarily exposed to high temperatures, such askitchen work plates.

The invention also provides a production method for a decorativelaminate substrate with a self-adhesive layer. The method of oneembodiment of this invention is characterized in that an adhesivematerial is applied on a laminate substrate at a temperature of 150-190°C., advantageously on the reverse side opposite from the decorative sideor layer, and is subsequently allowed to cool.

Advantageously, the adhesive is desirably applied on a continuouslyadvanced laminate with a stationary roller or nozzle. The adhesiveapplication rate on the laminate is desirably about 1 to 30 m/min.

The adhesive is preferably applied in a quantity of about 80 to about300 g/m², desirably about 140 to about 240 g/m², and more desirablyabout 150 to about 200 g/m², on the laminate substrate.

The applied adhesive is advantageously covered with a release layer,which advantageously is made of a siliconized paper or a siliconizedfilm.

In another embodiment of this invention, the laminate substrate has twodifferent adhesive layers applied thereon. A non-pressure sensitiveadhesive layer is first applied to one side of the laminate substrateand a self-adhesive layer is applied to the non-pressure sensitiveadhesive layer, and thereby indirectly applied to the laminatesubstrate. The self-adhesive layer includes a layer of a physicallysetting, solvent-free adhesive material comprising an acrylic polymer.The self-adhesive layer is desirably self-adhesive at room temperature.A release layer, such as a release paper or film, is desirably appliedover the self-adhesive layer to maintain the adhesive properties ortackiness until use.

The self-adhesive layer desirably includes a terpolymer of vinylacetate-ethylene and acrylic. The non-pressure sensitive adhesive layercomprises an adhesive material having a glass transition temperature ofabout 20° C. or greater. The non-pressure sensitive layer desirablyfunctions as a barrier layer or primer separating the self-adhesivelayer from the laminate substrate. The barrier provided by thenon-pressure sensitive adhesive desirably reduces or eliminatespenetration of the self-adhesive into the laminate substrate. In oneembodiment of his invention, the non-pressure sensitive adhesive is, forexample, polyvinyl acetate. The non-pressure sensitive adhesive layermay also be an acrylic primer as described below.

In one embodiment of this invention, the non-pressure sensitive adhesivelayer has an add-on level of about 10 to about 30 g/m², and theself-adhesive layer has an add-on level of about 75 to about 100 g/m².The non-pressure sensitive adhesive is desirably applied to the laminatesubstrate and subsequently at least partially cured or dried before theself-adhesive layer is applied over the applied non-pressure sensitiveadhesive. The layer of non-pressure sensitive adhesive desirablyprovides improved temperature resistance and extends the shelf life ofthe laminate before the final use or application to the carrier. Boththe self-adhesive layer and the non-pressure sensitive adhesive layercan be applied as, for example, a water-based emulsion, a solvent-basedemulsion, or a hot melt.

The adhesive-coated laminate substrate may be prepared by the followingmethod. First, a release layer is coated with a layer of physicallysetting, solvent-free adhesive which includes an acrylic polymer. Thismay be accomplished by initially coating the release layer with anaqueous or other solvent-based acrylic adhesive, suitably containingabout 35-75% by weight, or about 45-65% by weight adhesive solids. Thewater or other solvent is then removed by evaporation at about 30-150°C., suitably about 75-120° C. for a time of 1-15 minutes, or about 3-8minutes, sufficient to cause drying. The adhesive layer may have a drythickness of about 50-500 microns, or about 80-300 microns, and a wetthickness perhaps twice as large.

A suitable release layer is a silicone-coated paper, Type 402-6010,available from Wausau Paper Co. of Rhinelander, Wis. Various otherplastic-coated papers and plastic films can also be employed as releaselayers. The adhesive layer may be thermoplastic or thermosetting, and issuitably thermoplastic. Suitable adhesive polymers include withoutlimitation acrylic polymers, copolymers and terpolymers as describedabove.

Second, the adhesive can be applied to a surface of the laminatesubstrate by overlaying the adhesive-coated release layer on thelaminate substrate with the adhesive side facing the laminate substrate.If the laminate substrate is a cellulose-based high pressure laminate,or another laminate having a relatively smooth surface, it may bedesirable not to sand the surface or otherwise increase its roughnessprior to applying the adhesive. The solvent-free adhesive is relativelyviscous or solid and will not easily penetrate into the valleys andcrevices which are present in a rough surface. When the laminatesubstrate surface is relatively smooth, the adhesive may establishcontact over the entire surface, resulting in better adhesion.

Alternatively, the surface of the laminate substrate may be both sandedand primed before applying the adhesive. The sanding creates a roughsurface having valleys and crevices which are filled by coating with asuitable primer. Suitable primers include easy drying, solvent-basedprimers having polymer components which are compatible with the adhesiveto be applied. For instance, an acrylic-based primer dries to form anacrylic-based smooth surface which has excellent affinity to anacrylic-based adhesive layer. One suitable polyolefin-based primercontains about 50% by weight solids and is sold by Lord Chemlok underthe trade name 459X. The primer coating may have a dry thickness ofabout 10-50 microns, or about 15-40 microns, and a wet thickness perhapstwice as large. Once the primer is dried, the adhesive is applied to theprimed surface of the laminate substrate.

Third, pressure is applied to the release layer to press the adhesiveonto the surface of the laminate substrate. A suitable pressure isbetween about 3-70 N/cm², suitably about 10-50 N/cm². Once the adhesivehas been pressed onto the laminate substrate, the release layer ismanually peelable to expose the adhesive. For instance, the releaselayer can be manually peeled away and the adhesive layer can be used tobond the laminate substrate to a wall, floor, counter top, or othersurface.

FIG. 1 schematically illustrates an exemplary process 10 useful forcoating the adhesive layer onto the laminate substrate. An adhesivelayer 12, combined with a release layer 14, are unwound from a roll 16.The foregoing layers are brought together with laminate substrate 18 ina nip defined by nip rolls 20 and 22, with the adhesive layer 12 facingthe surface 17 of laminate substrate 18. Typically, laminate substrate18 is positioned so that the surface 17 is its back surface, i.e. thesurface used to bond adhesive-coated laminate substrate 28 to a wall,floor or object.

FIG. 2 schematically illustrates an alternative process 11 which issimilar to process 10 except for the presence of heaters. The adhesivelayer 12 may be heated using an external infrared heater 24 and/or aninternal heater (not shown) inside roll 20, before the adhesive layer 12is applied to and pressed onto the surface 17 of laminate substrate 18.Alternatively, or additionally, the laminate substrate 18 may be heatedusing infrared heater 26 before the adhesive layer 12 is applied. Ineither case, the heating may result in a temperature of about 30-120°C., suitably 50-80° C., which is high enough to soften the adhesivelayer 12 and impart a better adhesive bond to the laminate substrate 18.The release layer 14 can still be peelably removed to allow bonding ofadhesive-coated laminate substrate 28 to an object.

Examples of embodiments of this invention are described below, which, inno way, represent a limitation of the inventive idea.

1. Production of an Adhesive-Coated Laminate Substrate

All data refer to the weight.

From a supply container heated to 180° C., an adhesive based on 25% SIS,15% SBS, and 60% hydrocarbon resin (with a content of 10% polybutene),was conducted onto a roller with a width of 60 cm and heated to 180° C.The thermoplastically liquified adhesive was conveyed via the roller andapplied onto an HPL sheet, which was advanced with the roller at 15m/min, wherein the gap between the roller and the HPL sheet was 3 mm,and the adhesive was applied in a quantity of 180 g/m². A siliconizedpaper was applied for protection to the adhesive layer that was stillwarm. Subsequently, the HPL sheet coated with the adhesive was allowedto cool.

2. Application of the Adhesive-Coated Laminate Substrate on a CarrierMaterial

The above adhesive-coated laminate substrate was applied, at roomtemperature, on a carrier. The laminate, whose adhesive layer wascovered with a siliconized release paper, is first aligned on thecarrier. Subsequently, the release paper was pulled away, partially atan edge, preferably on the narrow edge, and the adhesive-coated laminatesubstrate was pressed on the carrier at the edge with the exposedadhesive layer. Then, the release paper was drawn out, step by step,under the adhesive-coated laminate substrate and the laminate substrateis pressed, manually, on the carrier. Advantageously, theadhesive-coated laminate substrate can be pressed uniformly on thecarrier substrate with a hard rubber roller. A subsequent processing ofthe edges can be done with the usual doctors, files, cutters, andgrinders.

3. Mechanical Characteristics of the Composite Material

Peeling-Off Resistance

Measurement values for the peeling-off resistance of a self-adhesiveHPL, in accordance with the invention, on various substrates, are shownbelow.

The determination of the peeling-off resistance is made according to EN311. The pressing of the adhesive-coated laminate substrate on thecarrier is carried out by light pressing manually or with a roller.

Peeling-off resistance Carrier material (N/mm²) Melamine-faced chipboard0.7-1.5 Wood materials (particle board, 0.7-1.5 plywood, multiplex,MDF), precoated with laminated sheets (HPL + CPL) Uncoated woodmaterials (particle 0.5-1.0 board, plywood, multiplex, MDF) Polystyrenefoam 0.2-0.5 Gypsum particle board 0.2-0.5 Expanded mica plates 0.2-0.5Aluminum, aluminum honeycombs 0.2-0.5

All measurement values given above are based on roughened HPL sheets. Asmooth HPL surface may result in somewhat higher peel resistance than aroughened surface if the adhesive is applied to the HPL surface in a drystate from a release layer, or somewhat lower peel resistance if theadhesive is applied to the HPL surface in a wet state.

Measurement of the Sheet Strength Loss Tempering

A laminate substrate with an adhesive layer according to one embodimentof this invention was cut to a size of 25 mm in width and 70 mm inlength. The test piece was applied on a carrier in such a way that therewas an overlapping of the adhesive area in the longitudinal direction of25 mm. On the free, lower end of the test piece, a weight of 500 g wasaffixed. Subsequently, the test setup was introduced into a furnace thatwas preheated to 40° C. and left there at 40° C. for 30 min. Then, thefurnace was heated at a heating rate of 0.37° C. per minute until thetest piece detached from the carrier.

Shear resistance loss temperatures between 60° C. and 105° C. weremeasured with adhesive-coated laminated sheets, in accordance with theinvention.

Further laminate samples (12.7 cm×20.3 cm) were prepared using:

1) FLEXBOND 153 to form a self-adhesive layer; and 2) FLEXBOND 153 toform a self-adhesive layer and polyvinyl acetate to form a non-pressuresensitive adhesive layer. The laminate samples were applied to a chipboard and/or melamine carrier and subjected to testing. The adhesivelayers were applied at about 5 mils (127 microns) and dried at 100° C.for 5 minutes.

The samples demonstrated temperature resistance upon application to acarrier by maintaining adhesion and laminate integrity to beyond 80° C.The samples were placed in an oven at 60° C. and the temperature wasraised ten degrees every two hours until delamination was observed.

The samples each further demonstrated a desirable long-term shelf lifeby maintaining laminate integrity at 75° C. beyond 1.5 months.

The samples demonstrated humidity resistance by maintaining laminateintegrity for over 14 days at 65° C. and a 95% humidity level.

The samples further demonstrated desirable shear strength by having apeeling-off force of over 0.2 N/mm² (e.g., about 0.26 and 0.35 N/mm²,respectively). The determination of the peeling-off resistance wasaccomplished according to EN 311. The pressing on the substrate iscarried out by light pressing manually or with a roller.

The invention illustratively disclosed herein suitably may be practicedin the absence of any element, part, step, component, or ingredientwhich is not specifically disclosed herein.

While in the foregoing detailed description this invention has beendescribed in relation to certain preferred embodiments thereof, and manydetails have been set forth for purposes of illustration, it will beapparent to those skilled in the art that the invention is susceptibleto additional embodiments and that certain of the details describedherein can be varied considerably without departing from the basicprinciples of the invention.

We claim:
 1. A high pressure decorative laminate, comprising in adjacentsequence: a hardened high pressure decorative laminate substrate havinga homogeneously closed structure and a density not less than about 1.35grams per cubic centimeter, consisting of layers of fibrous stripsimpregnated with a cured resin and one or more decorative paper layersimpregnated with a resin; an adhesive layer including a physicallysetting, solvent-free terpolymer of vinyl acetate-ethylene and acrylic,positioned adjacent to the hardened high pressure decorative laminatesubstrate; and a release layer including a siliconized paper or filmpositioned adjacent to the adhesive layer.
 2. The high pressuredecorative laminate of claim 1, wherein the adhesive layer isself-adhesive at room temperature.
 3. The high pressure decorativelaminate of claim 1, wherein the cured resin comprises at least one of amelamine resin, an epoxy resin, a phenoplastic, and a urea-formaldehyderesin.
 4. The high pressure decorative laminate of claim 3, wherein thecured resin comprises a melamine resin.
 5. The high pressure decorativelaminate of claim 1, wherein the fibrous strips comprise cellulosestrips.
 6. The high pressure decorative laminate of claim 1, wherein theadhesive layer comprises a non-pressure sensitive adhesive layeradjacent to the hardened high pressure decorative laminate substrate anda self-adhesive layer adjacent to the non-pressure sensitive adhesivelayer, the self-adhesive layer including the physically setting,solvent-free terpolymer of vinyl acetate-ethylene and acrylic.
 7. Thehigh pressure decorative laminate of claim 6, wherein the self-adhesivelayer further comprises an elastomer.
 8. The high pressure decorativelaminate of claim 7, wherein the elastomer comprises high molecularweight polyisobutylene rubber having a number-average molecular weightof about 300,000 to about 3,500,000 grams/mol.
 9. The high pressuredecorative laminate of claim 6, wherein the non-pressure sensitiveadhesive layer comprises polyvinyl acetate.
 10. The high pressuredecorative laminate of claim 1, wherein the layers of fibrous stripsimpregnated with a cured resin are bonded together under heat and highpressure of about 5 mPa or greater.
 11. The high pressure decorativelaminate of claim 10, wherein the fibrous strips impregnated with acured resin are bonded together at a temperature of about 120° C. toabout 150° C. and a pressure of about 7 mPa or greater.
 12. The highpressure decorative laminate of claim 1, wherein the adhesive layercomprises, based on dry weight, about 10 to about 70% by weight of anelastomer, about 10 to about 70% by weight of the terpolymer of vinylacetate-ethylene and acrylic, about 15 to about 40% by weight of aplasticizer, and about 15 to about 30% by weight of a hydrocarbon resin.13. The high pressure decorative laminate of claim 12, wherein theplasticizer comprises a low molecular weight polyisobutylene having amolecular weight of about 800 to about 5000 grams/mol.
 14. The highpressure decorative laminate of claim 12, wherein the elastomercomprises a block copolymer having two end blocks of a vinyl aromaticmonomer and at least one middle block that contains a conjugated dieneor is formed from an ethylene-butylene copolymer or anethylene-propylene copolymer.
 15. The high pressure decorative laminateof claim 14, wherein the end blocks have a molecular weight of about6000 to about 60,000 grams/mol and the middle block has a molecularweight of about 30,000 to about 150,000 grams/mol.
 16. The high pressuredecorative laminate of claim 12, wherein the hydrocarbon resin isselected from the group consisting of gum resin, wood resin, tallow oilresin, distillate resin, hydrogenated resin, dimerized resin,polymerized resin, and combinations thereof.